3190 - Impact of Bladder Filling on External Beam Radiotherapy for Prostate Cancer: A Mixed-Methods Analysis in a Large, Integrated Cancer Network

Purpose/Objective(s): Patients receiving definitive external beam radiation therapy (EBRT) for prostate cancer (PCa) typically prepare daily with a full bladder and empty rectum (FBER). Judging whether FBER prep is adequate is uncertain. This causes radiation therapists (RTTs) to acquire multiple cone-beam computed tomography (CBCT) scans, decreasing efficiency and causing patient frustration. We hypothesize that creating a minimally acceptable full bladder (BladderMin) for RTTs to reference would reduce the proportion of fractions exceeding the appointment slot as well as patient and RTT satisfaction.

Materials/Methods:

We distributed an eight-question survey to RTTs within our large, integrated cancer center network to describe FBER practice patterns, RTT job satisfaction, and potential value of the BladderMin protocol. A multi-center protocol was then implemented. The BladderMin structure was created by measuring the distance from the top of the pubic symphysis to the bladder dome at CT simulation. 1/3 of that distance and a 5mm radial margin were subtracted to create BladderMin. All BladderMin volumes met plan constraints. Fifteen patients treated prior to implementation were selected for quantitative assessment. We collected total treatment time, time per fraction, CBCTs per fraction, and CBCT rejections.

Results:

Of the 118 RTTs, we received 66 responses (56%). 92% agreed or strongly agreed that bladder filling is a common problem. 82% stated their current practice is to treat patients with bladder filling reasonably close to simulation and 12% require equal bladder filling with no exceptions. The most frequent reasons for failure of initial EBRT setup were rectal preparation (55%) or insufficient bladder filling (45%). 83% agreed or strongly agreed patients are frustrated when not treated on the first CBCT.

The historical cohort received 20-28 EBRT fractions (median 26.5) for a total of 356 fractions. Average fraction time was 10.8 minutes (range 3-85). 65 fractions (18%) required >15 minutes to deliver. 29 CBCTs (8%) were rejected by the treating physician. 102 fractions (29%) required >1 CBCT. RTTs agreed that a BladderMin protocol would improve patient care (Table 1).

Conclusion:

FBER preparation for EBRT for PCa is a source of patient and RTT frustration and can cause clinical inefficiency. A BladderMin protocol for EBRT for localized PCa may improve clinical care. Results of our post-implementation analysis to measure BladderMin impact on clinical efficiency and RTT job satisfaction will be provided with more mature follow-up.

Abstract 3190 - Table 1

Impact of BladderMin protocol	Yes (%)	No (%)	Not Sure (%)
Reduce uncertainty about bladder filling needs	97	3	--
Reduce # of CBCTs per treatment	89	8	3
Improve patient satisfaction	92	2	6
Improve RTT job satisfaction	88	3	9
Reduce radiation toxicity	66	3	31